+/**
+ * Helper function to decompress an image. The result is a 32-bpp RGBA
+ * image with stride==width.
+ */
+static void
+decompress_image(enum pipe_format format,
+ const uint8_t *src, uint8_t *dst,
+ unsigned width, unsigned height)
+{
+ const struct util_format_description *desc = util_format_description(format);
+ const uint bw = util_format_get_blockwidth(format);
+ const uint bh = util_format_get_blockheight(format);
+ const uint dst_stride = 4 * MAX2(width, bw);
+ const uint src_stride = util_format_get_stride(format, width);
+
+ desc->unpack_rgba_8unorm(dst, dst_stride, src, src_stride, width, height);
+
+ if (width < bw || height < bh) {
+ /* We're decompressing an image smaller than the compression
+ * block size. We don't want garbage pixel values in the region
+ * outside (width x height) so replicate pixels from the (width
+ * x height) region to fill out the (bw x bh) block size.
+ */
+ uint x, y;
+ for (y = 0; y < bh; y++) {
+ for (x = 0; x < bw; x++) {
+ if (x >= width || y >= height) {
+ uint p = (y * bw + x) * 4;
+ dst[p + 0] = dst[0];
+ dst[p + 1] = dst[1];
+ dst[p + 2] = dst[2];
+ dst[p + 3] = dst[3];
+ }
+ }
+ }
+ }
+}
+
+
+/**
+ * Helper function to compress an image. The source is a 32-bpp RGBA image
+ * with stride==width.
+ */
+static void
+compress_image(enum pipe_format format,
+ const uint8_t *src, uint8_t *dst,
+ unsigned width, unsigned height)
+{
+ const struct util_format_description *desc = util_format_description(format);
+ const uint dst_stride = util_format_get_stride(format, width);
+ const uint src_stride = 4 * width;
+
+ desc->pack_rgba_8unorm(dst, dst_stride, src, src_stride, width, height);
+}
+
+
+/**
+ * Software fallback for generate mipmap levels.
+ */